When birds collide with airplanes that are taking off or landing, the results can be catastrophic. And while there are deterrent systems that do work on some birds, they're not effective with raptors (aka birds of prey). According to new research, however, an optical illusion may do the trick.

In order to better understand how the birds react to different types of visual stimuli, scientists from the French National Center for Scientific Research and France's University of Rennes conducted over 300 tests on captive raptors. The researchers ultimately determined that just one pattern triggers avoidance behaviour. Consisting of concentric black circles on a white background, it reportedly creates a "looming" effect that causes the birds to believe that a collision is imminent.

The finding was put to the test at the Lourdes-Tarbes-Pyrénées Airport, which is located adjacent to the summer hunting grounds of raptors such as buzzards and kites. Two LED screens positioned at strategic points around the runways displayed the pattern throughout the day, causing the birds to avoid areas from which the screens could be seen. On the other hand, the raptors tended to congregate in areas where the screens weren't visible.

Even after the pattern had been continuously displayed for five weeks, the avoidance behaviour persisted. The system also appeared to deter corvids, a family which includes crows, ravens and magpies.

It is now hoped that the technology could be put into use not only at airports but also at wind farms, to keep birds from colliding with the turbine blades.

A paper on the research was recently published in the journal PLOS ONE.

Source: CNRS